146 
BRITISH ENTOMOSTRACA. 
this organization is fitted for both swimming and walking; 
the filaments assisting in the former, and the hooked claws 
at the extremity aiding in this latter purpose, enabling 
them to seize hold of the plants, &c. among which they 
live, and thus walk from place to place. Latreille con- 
siders these long filaments as acting, along with those of 
the superior antennae, the part of respiratory organs. 
The mouth is situate in the inferior surface of the an- 
terior lobe of the body, and consists of a lip, an inferior 
lip, a pair of palpiferous mandibles, and two pairs of jaws. 
The lip is composed of a large piece, shaped somewhat 
like a hood, forming a projection which advances between 
the two inferior antennae, and is fixed to the body by four 
long apophyses. The inferior lip is elongated, triangular, 
and moveable ; is articulated with the lip, and has at its 
extremity two curved apophyses to articulate it with the 
second pair of jaws. 
The mandible (t. XVIII, f . 1 d) is very large, and is 
formed of two pieces. The larger, or mandible properly so 
called, is terminated at its superior extremity by a point, and 
at the lower or incisive extremity by five pretty strong teeth. 
The other piece is in form of a palpus, which issues from 
about the middle length of the proper mandible, and 
consists of three joints provided with several setae. The 
first joint has near its base a very small branchial plate 
terminated by five digitations. This palpiform part of 
the mandible is the second pair of feet of Jurine, the 
barbillon of Muller ; the use of which, both agree, is to 
cause a current of water towards the mouth, carrying 
with it the particles destined for the animal’s food. The 
first pair of jaws (t. XVIII, f. 1 e) have for their base a 
large square plate, furnished at anterior extremity with four 
fingers, the superior of which is of two joints, the other 
three having only one each, but all terminated by several 
long hairs. From the external edge of this plate, forming 
the base, arises a large, elongated, branchial plate (f. 1 e*), 
which gives off from the superior crescentic-shaped edge 
a row of nineteen long spines, arranged like the teeth of 
